c++中ifstream一次读取整个文件

c++中一次读取整个文件的内容的方法：

1. 读取至char*的情况

 std::ifstream t;
 int length;
 t.open("file.txt");      // open input file
 t.seekg(0, std::ios::end);    // go to the end
 length = t.tellg();           // report location (this is the length)
 t.seekg(0, std::ios::beg);    // go back to the beginning
 buffer = new char[length];    // allocate memory for a buffer of appropriate dimension
 t.read(buffer, length);       // read the whole file into the buffer
 t.close();                    // close file handle

 // ... do stuff with buffer here ...

2. 读取至std::string的情况

第一种方法：

 #include <string>
 #include <fstream>
 #include <streambuf>

 std::ifstream t("file.txt");
 std::string str((std::istreambuf_iterator<char>(t)),
                  std::istreambuf_iterator<char>());

第二种方法：

 #include <string>
 #include <fstream>
 #include <sstream>
 std::ifstream t("file.txt");
 std::stringstream buffer;
 buffer << t.rdbuf();
 std::string contents(buffer.str());

reference:  http://stackoverflow.com/questions/2602013/read-whole-ascii-file-into-c-stdstring

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